Electric circuit interrupter



March 21, 1939. K. lSHlWATA 2,151,551

ELECTRIC CIRCUIT INTERRUPTER Filed May 6, 1937 q/L LEVEL Fig.2.

Inventor: Kiichi Ishiwata,

Attorney.

Patented Mar. 21, 1939 ELECTRIC CIRCUIT INTERRUPTER Kiichi Ishiwata, Kanagawaken, Japan, assignor to General Electric Company, a corporation of New York Application May 6, 193' Serial No. 141,174 In Japan May 20, 1936 Claims.

My invention relates to electric circuit interrupters of the fluid-blast type. such as oil blast circuit breakers, for example, wherein arc pressure generated upon opening of the circuit is 5 utilized for directing an extinguishing blast of fluid through the arc.

In a well-known form of oil blast circuit breaker two arcs are formed in series upon opening of the circuit by relatively movable contact structure including a comparatively fixed contact, an intermediate contact mounted for limited movement with respect to said fixed contact, and a movable contact arranged to engage said intermediate contact and bias the same into engagement with said fixed contact. This contact structure is disposed within a pressure confining chamber which is filled with oil and designed so that the arc pressure formed at the first break between the fixed and intermediate contacts is effective to direct an arc-extinguishing blast of oil across the second break between the intermediate and movable contacts. This form of oil blast breaker is very effective, but is expensive and somewhat complicated in design as compared with a plain-break switch by reason of the relatively movable intermediate contact structure.

A principal object of my invention is the provision of an improved circuit interrupter of the aforesaid type which is comparatively simple and compact in design, efiicient and positive in operation, and which involves a minimum of displaceable or moving parts.

In accordance with my invention, a part of the are formed between relatively movable contacts, or the equivalent thereof, during opening of the circuit, is displaced or driven in the direction of a pressure-confining chamber containing an arcextinguishing liquid so as to cause generation of arc pressure within said chamber, and this pressure is so directed that a blast of said liquid is driven through another part of the arc. In a preferred embodiment of my invention a fixed intermediate contact is disposed along the path of separation of a pair of relatively mov-' (o1. zoo- 150) companying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Figure 1 is an elevational fragmentary view, partly in section, of one pole of an electric circuit breaker embodying the present invention; and Fig. 2 is a partly diagrammatic plan view of part of the circuit breaker structure.

The circuit interrupter shown by way of example comprises an oil circuit breaker of wellknown general form wherein a pair of stationary contact structures, one of which is indicated at l are interconnected in the closed circuit position by a bridging member 2 which is operated in a vertical direction by a lift rod 3. The relatively movable contact structure above described is immersed in a suitable arc-extinguishing liquid, such as oil, for example.

The stationary contact structure 1 comprises a lead-in conductor 4 mounted in an insulating bushing 5 and terminating in a fixed contact 6 having a contact-making surface at 6' for coaction with the contact element 2 of the bridging member. Associated with the fixed contact 6 is an arc-extinguishing structure or casing I .which comprises in part an expulsion chamber formed of suitable insulating material mounted on the contact 6. The insulating structure I is partly open at the side adjacent the bridging contact for permitting free movementpf the contact 2 between open and closed circuiiipositions. Preferably the bridging member 2 has but a limited clearance with respect to the insulating side walls so that it is vertically movable in a slot, as illustrated. The casing is substantially closed at its other sides.

Within the insulating structure I there is formed a pressure confining chamber 8 which is adjacent and slightly offset with respect to the path of movement of the contact element 2. The pressure confining chamber 8 is defined mainly by the casing wall I, an intermediate contact 9 which forms with the contact 6 a small opening at l0 in the side wall of the chamber adjacent the arc, and a. lower insulating wall or partition ll. The insulating wall H is provided with an opening I! which serves as an exhaust port for the chamber 8 communicating with a passage l3 which extends transversely of the lower path of movement of the contact 2.

When the circuit breaker is in the closed circuit position, as indicated by the dotted line posltion of the bridging member the chamber openchamber exhaust port l2, issubstantially closed) by the bridging member. At the start oi! the circuit-opening operation separation of the contacts 2' and 6 causes an arc to form between these contacts adiacent the intermediate contact 9. It will be apparent that as the bridging contact is lowered beyond the intermediate contact the arc will transfer to the contact 9 and form in two sections between the fixed andmovable contacts.

For the purpose of creating arc pressure within the chamber so as to drive a blast of oil by way of the exhaust port and passage l2l3 through the lower section of the arc, there is provided electromagnetic means for displacing the initial part of the arc in the direction of the chamber opening ll. The electromagnetic device may take the form of a U-shaped member ll composed of iron or other suitable magnetic material embedded in the insulating material of the chamber casing I as illustrated, so that the arc is drawn between the outer arms of the member. For reasons well known in the art, the interacting magnetic fields so produced tend to displace or drive the are as indicated at I! along the surfaces of the contacts 0 and 9 farther into the magnetic loop and into the chamber 8. This is diagrammatically illustrated by Fig. 2. It will be apparent that the arcing surfaces of the contacts can be shaped so as to produce the desired length of pressure generating are as indicated, for example, by the electrode surface 9.

The are pressure created within the chamber 8 exhausts chiefly through the port i2 by reason of the restricted opening at ill, so that an oil blast is driven through the passage it across the other section of the are indicated at it. This oil blast serves to interrupt the main part of the arc and open the circuit in an eiiective manner.

It will be apparent that it is within the scope of the present invention to multiply the number oi oil blast chambers, if desired, where the interrupting requirements 01' the circuit make a multiple arrangement advantageous.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit oi my invention.

What I claim as new and desire to secure by Letters Patent oi the United States is:

1. An electric circuit interrupter of the fluid blast type comprising means for forming an arc within an arc extinguishing fluid, a pressure confining chamber having an opening adjacent to one portion of said arc, means for driving said portion oi arc through said opening and into said chamber to generate arc pressure therein, said driving means being increasingly responsive to the magnitude of the current to be interrupted, and means for directing said are pressure in said chamber to cause a fluid blast at another portion of said arc, said blast exhausting from said chamber at a point other than said opening.

2. An electric circuit interrupter of the fluid blast type comprising separable contacts, arc extinguishing structure including a pressure confining chamber having an opening adjacent to 2,151,551 ing in, which is restricted as compared with the that portion of the are initially formed and an exhaust opening'separate therefrom, conducting means adjacent to and fixed with respect to said opening forming a terminal of said portion 01' arc, electromagnetic means for causing displacement of said initial portion of said are through said opening and into said chamber to generate arc pressure therein, and means for directing fluid under influence of said are pressure from said exhaust opening through a subsequently formed portion of said are.

3. An electric circuit breaker of the liquid blast type comprising relatively movable contacts separable within an arc-extinguishing liquid, arc interrupting structure associated with said contacts including a chamber having an opening adjacent and immediately opposite a portion of the arc initially formed between said contacts upon opening of the circuit, means responsive to all values oi the current to be interrupted to displace that portion of said are into said chamber so as to cause generation of arc pressure within said chamber, said chamber having a separate exhaust opening other than said first-named opening for directing arc-extinguishing liquid through another part of said arc.

4. An electric circuit breaker of the liquid blast type comprising relatively movable contacts separable within an arc-extinguishing liquid, arcextinguishing structure associated with one oi said contacts including a pressure-confining chamber, said chamber having an opening adjacent to the point of initial contact separation, an intermediate contact arranged to be substantially at said opening, said intermediate contact having a substantially fixed relation to said one 01' said contacts and to said chamber so as to form a pressure generating arc at the opening of said chamber, and electromagnetic means increasingly responsive to increase in current for driving said are through said opening and into said chamber so as to cause generation of arc pressure therein, said chamber having an exhaust opening other than said first opening for directing arc-extinguishing liquid through another part of said arc.

5. An electric circuit breaker of the liquid blast type comprising fixed and movable contacts, areinterrupting structure forming a pressure-confining chamber associated with said fixed contact, said chamber having an opening adjacent and immediately opposite a part of the arc initially formed at said fixed contact, an intermediate contact disposed along the path of separation of said fixed and movable contacts so as to form two arcs in series upon opening of the circuit, said intermediate contact being arranged with respect to said chamber opening so that said initial part of the arc is formed exteriorly of said chamber, and means for creating a magnetic field adjacent said initial part of said are for driving said are through said opening into said chamber for causing generation of arc pressure therein, the driving force of said field being a maximum at high current values, said chamber having a separate exhaust opening other than said first opening for directing arc-extinguishing liquid through the second part of said arc.

KIICHI ISHIWATA. 

